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% Construction
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\section{Construction}

\subsection{Chassis}
Tha basis in the chassis is a flat aluminium plate with L-shaped plates by along the sides for support. Its on the underside of this contruction the motors are attached. The main plate is almost at the distance of the radius of the wheel above the floor. Under the main plate, at the back, there is a special construction where to put the battery but also where the castor wheel is attached. From this we gain wheight from the battery to the back where the castor wheel is located to reduce the risk of falling forward.
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The roboard is attached on the main plate in the center so cables and connections will be protected and fixated by the border plate that almost encircles the area above the main plate.
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On this border plate there is a flat plate that is easy to take away and put back to be able to work with the elektronics inside as this plate encloses the space within. On this top plate there are four small constructions on each side where the IR-sensors are being attached. The extra construction has the function to bring the sensors out as much as possible to the sides and to the front and back. One reason for this is to have more different readings from two opposite sensors which in the end will make it easier to measure the angle the robot has to a wall. Another reason with the sensors on the sides is to detect walls at the sides easily. A third reason is that when the robot is going along a wall and finds a hole in it it will be easier to determine the size of the hole and where to stop before turning (if going through the hole).
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\begin{figure}[!htb]
\centering
\includegraphics[width = 0.5\textwidth]{pic/robot3}
\caption{Robot from above}
%\label{pic:path_2}
\end{figure}

\begin{figure}
\centering
\begin{minipage}[hbt]{0.45\textwidth}
	\centering
	\includegraphics[width=\textwidth]{pic/robot1}
	\caption{Robot back}
%	\label{pic:path_3}
\end{minipage}
\hfill
\begin{minipage}[hbt]{0.45\textwidth}
	\centering
	\includegraphics[width=\textwidth]{pic/robot2}
	\caption{Robot side}
%	\label{pic:path_4}
\end{minipage}
\end{figure}

To have the camera in a better position considering the height of the tags a tower is at the top of the top plate where the camera is attached.
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In the front of the robot there is a bumper with curvy shape. The shape is designed considering that it shouldn't stick out to much it will touch the walls in vain. The bumper cover the ost of the front area but not the sides as the IR-sensors will have a good view there and to make it take less space. Two parallel switches are being used to make it more robust.
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The robot were also modified with extra weights at the back to make it less likely to tip forward.

